Samim Khan

A novel method for copper(II) mediated region-selective bromination of aromatic rings under mild conditions

A tridentate N2O donor Schiff base is used as the substrate and copper(II) perchlorate and potassium bromide have been used as reagents. In the resulting copper(II) Schiff base complex, the 4 position of the aromatic ring of the Schiff base moiety is brominated. X-ray single crystal diffraction study confirms the structure of the complex. In the conventional bromination of aromatic substrates with bromine as the reagent, a potential pollutant hydrobromic acid is produced as a by-product. The present method provides an alternative environmentally friendly route for the bromination of an activated aromatic ring. Regioselectivity of the bromination in the ligand have been studied using DFT calculations.

End-on cyanate or end-to-end thiocyanate bridged dinuclear copper(II) complexes with a tridentate Schiff base blocking ligand: synthesis, structure and magnetic studies

Two dinuclear copper(II) complexes, [Cu2(L)2(μ1,1-NCO)2] (1) and [Cu2(L)2(μ1,3-NCS)2]·H2O·DMF (2), have been synthesized using a tridentate N2O donor Schiff base ligand (HL), [1((2-(ethylamino)ethylimino)methyl)naphthalen-2-ol], and characterized by elemental analysis, spectral study and X-ray crystallography. Both complexes are centrosymmetric dimers in which square pyramidal copper(II) centres are connected by pseudo-halides: end-on cyanate in 1 and end-to-end (EE) thiocyanate in 2. Variable temperature (2–300 K) magnetic susceptibility measurements indicate the presence of ferromagnetic exchange coupling between copper(II) centres in complex 1 (J = 0.97 cm−1), and antiferromagnetic exchange coupling in 2 (J = −0.6 cm−1).

A mixed phenoxo and end-on azide bridged dinuclear copper(II) Schiff base complex: synthesis, structure, magnetic characterization and DFT study

A dinuclear copper(II) complex, [(H2O)Cu(L)(μ1,1-N3)Cu(L)]ClO4 [HL = (2-(2-(ethylamino)ethylimino)methyl)-6-ethoxyphenol] has been synthesized and characterized by spectral and elemental analyses. The structure has been confirmed by single crystal X-ray diffraction. Variable temperature (2–300 K) magnetic susceptibility measurements indicate the presence of antiferromagnetic exchange coupling between the copper(II) centers (J = −46.18 cm−1), as also corroborated by DFT calculations (Jtheo = −45.98 cm−1). The calculated spin densities at the copper(II) centers were +0.56 and −0.61, confirming that they are the magnetic centers. An experimental absorption spectrum of the complex has been compared with a normalized absorption spectrum obtained theoretically. Supramolecular interactions in the solid state of the complex have also been characterized with the help of Hirshfeld analysis and the AIM theory.